scholarly journals An Aptamer-Based Biosensor for Direct, Label-Free Detection of Melamine in Raw Milk

Sensors ◽  
2018 ◽  
Vol 18 (10) ◽  
pp. 3227 ◽  
Author(s):  
Naoto Kaneko ◽  
Katsunori Horii ◽  
Joe Akitomi ◽  
Shintaro Kato ◽  
Ikuo Shiratori ◽  
...  
Keyword(s):  
Sample Preparation ◽  
Background Noise ◽  
Colorimetric Detection ◽  
Raw Milk ◽  
Detection Methods ◽  
Label Free ◽  
Label Free Detection ◽  
High Concentrations ◽  
Direct Label ◽  
Urinary Problems

Melamine, a nitrogen-rich compound, has been used as a food and milk additive to falsely increase the protein content. However, melamine is toxic, and high melamine levels in food or in milk can cause kidney and urinary problems, or even death. Hence, the detection of melamine in food and milk is desirable, for which numerous detection methods have been developed. Several methods have successfully detected melamine in raw milk; however, they require a sample preparation before the analyses. This study aimed to develop an aptamer-DNAzyme conjugated biosensor for label-free detection of melamine, in raw milk, without any sample preparation. An aptamer-DNAzyme conjugated biosensor was developed via screening using microarray analysis to identify the candidate aptamers followed by an optimization, to reduce the background noise and improve the aptamer properties, thereby, enhancing the signal-to-noise (S/N) ratio of the screened biosensor. The developed biosensor was evaluated via colorimetric detection and tested with raw milk without any sample preparation, using N-methylmesoporphyrin IX for fluorescence detection. The biosensor displayed significantly higher signal intensity at 2 mM melamine (S/N ratio, 20.2), which was sufficient to detect melamine at high concentrations, in raw milk.

scholarly journals Affinity Sensors for the Diagnosis of COVID-19

Micromachines ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 390
Author(s):  
Maryia Drobysh ◽  
Almira Ramanaviciene ◽  
Roman Viter ◽  
Arunas Ramanavicius
Keyword(s):  
Field Effect Transistors ◽  
Resonance Field ◽  
Analytical Signal ◽  
Nucleic Acid Hybridization ◽  
Detection Methods ◽  
Label Free ◽  
Infected People ◽  
Label Free Detection ◽  
Main Instrument ◽  
Antigen Antibody

The coronavirus disease 2019 (COVID-19) outbreak caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was proclaimed a global pandemic in March 2020. Reducing the dissemination rate, in particular by tracking the infected people and their contacts, is the main instrument against infection spreading. Therefore, the creation and implementation of fast, reliable and responsive methods suitable for the diagnosis of COVID-19 are required. These needs can be fulfilled using affinity sensors, which differ in applied detection methods and markers that are generating analytical signals. Recently, nucleic acid hybridization, antigen-antibody interaction, and change of reactive oxygen species (ROS) level are mostly used for the generation of analytical signals, which can be accurately measured by electrochemical, optical, surface plasmon resonance, field-effect transistors, and some other methods and transducers. Electrochemical biosensors are the most consistent with the general trend towards, acceleration, and simplification of the bioanalytical process. These biosensors mostly are based on the determination of antigen-antibody interaction and are robust, sensitive, accurate, and sometimes enable label-free detection of an analyte. Along with the specification of biosensors, we also provide a brief overview of generally used testing techniques, and the description of the structure, life cycle and immune host response to SARS-CoV-2, and some deeper details of analytical signal detection principles.

scholarly journals Electrochemical DNA Detection Methods to Measure Circulating Tumour DNA for Enhanced Diagnosis and Monitoring of Cancer

Proceedings ◽  
2020 ◽  
Vol 60 (1) ◽  
pp. 15
Author(s):  
Bukola Attoye ◽  
Matthew Baker ◽  
Chantevy Pou ◽  
Fiona Thomson ◽  
Damion K. Corrigan
Keyword(s):  
Point Of Care ◽  
Low Cost ◽  
Detection Methods ◽  
Clinical Samples ◽  
Label Free ◽  
Ambient Conditions ◽  
Liquid Biopsies ◽  
Current Time ◽  
Electrochemical Approach ◽  
Label Free Detection

Liquid biopsies are becoming increasingly important as a potential replacement for existing biopsy procedures which can be invasive, painful and compromised by tumour heterogeneity. This paper reports a simple electrochemical approach tailored towards point-of-care cancer detection and treatment monitoring from biofluids using a label-free detection strategy. The mutations under test were the KRAS G12D and G13D mutations, which are both important in the development and progression of many human cancers and which have a presence that correlates with poor outcomes. These common circulating tumour markers were investigated in clinical samples and amplified by standard and specialist PCR methodologies for subsequent electrochemical detection. Following pre-treatment of the sensor to present a clean surface, DNA probes developed specifically for detection of the KRAS G12D and G13D mutations were immobilized onto low-cost carbon electrodes using diazonium chemistry and 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride/N-hydroxysuccinimide coupling. Following the functionalisation of the sensor, it was possible to sensitively and specifically detect a mutant KRAS G13D PCR product against a background of wild-type KRAS DNA from the representative cancer sample. Our findings give rise to the basis of a simple and very low-cost system for measuring ctDNA biomarkers in patient samples. The current time to result of the system was 3.5 h with considerable scope for optimisation, and it already compares favourably to the UK National Health Service biopsy service where patients can wait weeks for their result. This paper reports the technical developments we made in the production of consistent carbon surfaces for functionalisation, assay performance data for KRAS G13D and detection of PCR amplicons under ambient conditions.

scholarly journals Silicene Quantum Capacitance Dependent Frequency Readout to a Label-free Detection of DNA Hybridization

2021 ◽  
Author(s):  
Sazzadur Rahman ◽  
Rokaia Laizu Naima ◽  
Khatuna Jannatun Shetu ◽  
Mahabub Hossain ◽  
M. Shamim Kaiser ◽  
...  
Keyword(s):  
Band Gap ◽  
Dna Hybridization ◽  
Glucose Sensor ◽  
Detection Method ◽  
Genetic Research ◽  
Ph Sensor ◽  
Detection Methods ◽  
Quantum Capacitance ◽  
Label Free ◽  
Label Free Detection

Two-dimensional silicon allotrodes– also called Sinicene– have recently experienced intensive scientific research interest due to their unique electrical, mechanical, and sensing characteristics. A novel silicene based nano-material has been enticed great amenities, partially because of its uniformity with graphene. Silicene is a highly sensitive for numerous sensors based on molecular sensing as pH sensor, gas sensor, ion sensor and biosensing are Deoxyribonucleic acid (DNA) nucleobase sensor, photonic sensor, cell-based biosensor, glucose sensor, and bioelectric nose sensor. Nowadays genetic research based on DNA hybridization, which is a vital tools for sensing material and it has various detection methods. Among of them, the detection method is frequency readout used to a label-free detection of DNA hybridization. In this paper we have compared the graphene and silicene quantum capacitance that has been proposed for a DNA hybridization detection method on wireless readout. These method shows, the strands of mismatched and complementary DNA have in different range of frequency to identify output efficiency. With respect to DNA concentration the output of silicene is almost sharply linear than graphene. In addition of field effect transistor, silicene opens a new opportunities due to its band gap whereas graphene indicates zero band gap. It can be stated that silicene is much more reliable as well as much stronger than multi-layered graphene.

scholarly journals Protein Binding Characteristics of the Principal Green Tea Catechins: A QCM Study Comparing Crude Extract to Pure EGCG

2019 ◽  
Vol 2019 ◽  
pp. 1-8
Author(s):  
Elsadig E. Ali ◽  
Mohamed O. Elmakki ◽  
Miranda L. Gavette ◽  
Brian J. Doyle ◽  
Shannon J. Timpe
Keyword(s):  
Protein Binding ◽  
Green Tea ◽  
Crude Extract ◽  
Chemical Constituents ◽  
Epigallocatechin Gallate ◽  
Protein Molecule ◽  
Detection Methods ◽  
Label Free ◽  
Binding Characteristics ◽  
Label Free Detection

Label-free detection methods such as the quartz crystal microbalance (QCM) are well suited to the analysis of molecular interactions in complex mixtures such as crude botanical extracts. In the present study, the binding characteristics of epigallocatechin gallate (EGCG) and crude green tea extract solutions to bovine serum albumin (BSA) have been investigated. The adsorbed mass levels onto BSA-functionalized surfaces were measured at various solution concentrations. Langmuir and Freundlich isotherms were used to model the adsorption data. The Langmuir isotherm better described the adsorption behavior with correlations of 0.68 and 0.70 for the EGCG and the crude extract solutions, respectively. The better fit of the Langmuir model indicates that adsorption occurs homogeneously and that aggregation is negligible. The mass saturation is estimated to be 58% higher for the crude green tea solution as compared to the pure EGCG solution (7.9 ng/cm2 for green tea and 5 ng/cm2 for EGCG). The increased adsorption for the crude extract indicates that the additional tea chemical constituents are binding to alternate sites on the protein molecule and that competitive binding is a nondominant effect. However, a reduced adsorption rate for the crude extract was also observed, indicating some presence of competitive mechanisms. The results demonstrate the utility of the QCM for the analysis of protein binding in crude mixtures as well as pure compounds.

THE APPLICATION PROSPECT OF MICROCANTILEVER SENSORS TECHNOLOGY ON MINERAL SURFACE ADSORPTION

2019 ◽  
Vol 26 (07) ◽  
pp. 1830010
Author(s):  
FEI FANG ◽  
FANFEI MIN ◽  
CHANGGUO XUE ◽  
JIA DU
Keyword(s):  
High Sensitivity ◽  
Fast Response ◽  
Detection Methods ◽  
Mineral Surfaces ◽  
Label Free ◽  
Microcantilever Sensors ◽  
Label Free Detection ◽  
Potential Applications ◽  
Working Principle ◽  
Interfacial Adsorption

The main purpose of this review is to present a new method to study the adsorption mechanism of reagents on mineral surfaces based on a microcantilever sensor system. The mechanisms of micro/nanoscale adsorption are of great significance in the interface sorting of minerals in the field of mineral processing. The sensing technique based on a microcantilever has become attractive with the advantages of label-free detection, high sensitivity, high-throughput, and fast response time. This review first discusses the structure, working principle, working modes, detection methods, and reported applications of microcantilever sensors. When combined with the working principle and applications, microcantilever sensors can monitor the adsorption process of reagents on mineral surfaces in real time. In the second part of this review, we will discuss the potential applications of microcantilever sensors in the interfacial adsorption of minerals.

Formation of porous Cu hydroxy double salt nanoflowers derived from metal–organic frameworks with efficient peroxidase-like activity for label-free detection of glucose

Nanoscale ◽  
2018 ◽  
Vol 10 (25) ◽  
pp. 11948-11954 ◽  
Author(s):  
Ali Li ◽  
Xijiao Mu ◽  
Tianrong Li ◽  
Huang Wen ◽  
Wanchong Li ◽  
...  
Keyword(s):  
Colorimetric Detection ◽  
Metal Organic Frameworks ◽  
Copper Acetate ◽  
Double Salt ◽  
Label Free ◽  
Label Free Detection ◽  
Metal Organic

With a leaf-like MOF-5 as both a precursor and a template and copper acetate as a second precursor, CuHDS nanoflowers have been prepared for colorimetric detection of glucose.

Real-Time, Label-Free Detection of Local Exocytosis Outside Pancreatic β Cells Using Laser Tweezers Raman Spectroscopy

2016 ◽  
Vol 71 (3) ◽  
pp. 422-431 ◽  
Author(s):  
Rui-qiong Luo ◽  
Fang Wei ◽  
Shu-shi Huang ◽  
Yue-ming Jiang ◽  
Shan-lei Zhang ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Negative Control ◽  
Laser Tweezers ◽  
Channel Blockers ◽  
Label Free ◽  
Β Cells ◽  
Pancreatic Β Cells ◽  
Low Concentrations ◽  
Label Free Detection ◽  
High Concentrations

The examination of insulin (Ins) exocytosis at the single-cell level by conventional methods, such as electrophysiological approaches, total internal reflection imaging, and two-photon imaging technology, often requires an invasive microelectrode puncture or label. In this study, high concentrations of glucose and potassium chloride were used to stimulate β cell Ins exocytosis, while low concentrations of glucose and calcium channel blockers served as the blank and negative control, respectively. Laser tweezers Raman spectroscopy (LTRS) was used to capture the possible Raman scattering signal from a local zone outside of the cell edge. The results show that the frequencies of the strong signals from the local zones outside the cellular edge in the stimulated groups are greater than those of the control. The Raman spectra from the cellular edge, Ins and cell membrane were compared. Thus, local Ins exocytosis activity outside pancreatic β cells might be observed indirectly using LTRS, a non-invasive optical method.

Direct label-free detection of Rotavirus using a hydrogel based nanoporous photonic crystal

RSC Advances ◽  
2016 ◽  
Vol 6 (9) ◽  
pp. 7384-7390 ◽  
Author(s):  
Bohee Maeng ◽  
Youngkyu Park ◽  
Jungyul Park
Keyword(s):  
Photonic Crystal ◽  
Crystal Structures ◽  
Virus Detection ◽  
Label Free ◽  
Label Free Detection ◽  
Near Future ◽  
Direct Label

A direct label-free biosensor based on 3D photonic crystal structures for Rotavirus has been demonstrated. This proposed method will be useful for developing a direct and easy-to-use virus detection kit in the form of POCT in the near future.

Direct Label Free Detection of Orchid Virus Using a Micro/Nano Hybrid Structured Biosensor

2019 ◽  
Author(s):  
Wei-Jhen Wang ◽  
Chia-Hwa Lee ◽  
Chin-Wen Li ◽  
Stephen Liao ◽  
Fuh-Jyh Jan ◽  
...  
Keyword(s):  
Label Free ◽  
Self Assembled Monolayer ◽  
Detection Range ◽  
Elisa Kit ◽  
Detection Approach ◽  
Linear Detection ◽  
Label Free Detection ◽  
Semiconductor Fabrication ◽  
Direct Label ◽  
Higher Sensitivity

Abstract In this study, a label-free detection approach for effective detection of the odontoglossum ringspot virus (ORSV) infected orchids has been developed. We used semiconductor fabrication process to fabricate 1,810 micro/nano hybrid structured sensing electrodes on a 8 inch reclaimed wafer. The self-assembled monolayer (SAM) process was then employed to sequentially modify the electrode surface with 11-mercaptoundecanoic acid (11-MUA), 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC)/ N-hydroxysuccinimide (NHS), anti-ORSV, and ORSV. EIS was conducted for the ORSV concentration detection. Experimental results demonstrated that the ORSV concentration in a virus infected orchid leaf could be effectively detected. When compared with the ELISA kit, our device possesses a wider linear detection range (0.5–50,000 ng/mL) and a higher sensitivity. The specificity of our device on ORSV detection was also confirmed. Our sensing device retains advantages, such as label-free, lower amounts of the antibody and target sample required, low detection time, and a wider linear detection range. Those results imply the feasibility of our sensing device in field applications.

scholarly journals Advances in Label-Free Detections for Nanofluidic Analytical Devices

Micromachines ◽  
2020 ◽  
Vol 11 (10) ◽  
pp. 885 ◽  
Author(s):  
Thu Le ◽  
Hisashi Shimizu ◽  
Kyojiro Morikawa
Keyword(s):  
Single Molecule ◽  
Detection Methods ◽  
Label Free ◽  
Practical Applications ◽  
Detection Techniques ◽  
Kinetic Information ◽  
Label Free Detection ◽  
Nanofluidic Devices ◽  
Nanofluidic Device ◽  
New Research

Nanofluidics, a discipline of science and engineering of fluids confined to structures at the 1–1000 nm scale, has experienced significant growth over the past decade. Nanofluidics have offered fascinating platforms for chemical and biological analyses by exploiting the unique characteristics of liquids and molecules confined in nanospaces; however, the difficulty to detect molecules in extremely small spaces hampers the practical applications of nanofluidic devices. Laser-induced fluorescence microscopy with single-molecule sensitivity has been so far a major detection method in nanofluidics, but issues arising from labeling and photobleaching limit its application. Recently, numerous label-free detection methods have been developed to identify and determine the number of molecules, as well as provide chemical, conformational, and kinetic information of molecules. This review focuses on label-free detection techniques designed for nanofluidics; these techniques are divided into two groups: optical and electrical/electrochemical detection methods. In this review, we discuss on the developed nanofluidic device architectures, elucidate the mechanisms by which the utilization of nanofluidics in manipulating molecules and controlling light–matter interactions enhances the capabilities of biological and chemical analyses, and highlight new research directions in the field of detections in nanofluidics.

Sign in / Sign up

Export Citation Format

Share Document